Item: Faceting above crusts and associated slab avalanching in the columbia mountains
Title: Faceting above crusts and associated slab avalanching in the columbia mountains
Proceedings: Proceedings of the 2004 International Snow Science Workshop, Jackson Hole, Wyoming
Authors: Bruce Jamieson and Paul Langevin, Dept. of Civil Engineering, Dept. of Geology and Geophysics, University of Calgary, Calgary, Alberta
Abstract: Numerous slab avalanches including unexpected human triggered avalanches are reported on crusts. For 70 dry slab avalanches that slid on a crust in the Columbia Mountains of western Canada, detailed profiles showed faceted crystals (60%) or surface hoar (33%) on the crust. Many of the facet layers were thin (<5-10 mm thick) and difficult to observe in manual snow profiles without snowpack tests. Two field studies with closely spaced thermistors showed faceting at the base of the overlying dry snow within a day. One time series of shear frame tests of facets-on-crust showed an initial strength loss during faceting followed by a slow strength increase. Observations of the spatial distribution of near crust faceting are summarized.
Keywords: avalanche forecasting, snowpack stratigraphy, crusts, melt-freeze layers, faceted crystals
Digital Abstract Not Available